New World screwworm (NWS) is a nasty flesh-eating parasite that feeds on the living tissue of animals. Once infected, the parasites can cause severe infection and death in livestock.
The U.S. had successfully kept NWS out since 1966, but cases have been rising rapidly in Mexican cattle over the past year. A few weeks ago, the first U.S. case was found in a calf in South Texas, near the border. As of June 16th there were 12 confirmed cases, mostly in Texas cattle but also in goats, sheep, and one pet dog in New Mexico.
You can absolutely continue to sell and serve beef, it will just be expensive. NWS isn’t generally considered a food safety issue. The screwworms don’t actually infest meat (only living tissue), and FSIS inspections add another layer to prevent meat from infected cattle from entering the food supply. Still, it’s a major concern for the livestock and beef industries - particularly rough with beef already at record high prices before this (not to mention avian flu picking back up this month in dairy cows in Idaho, Texas, and Utah). The pace at which cattle have been affected in Mexico is concerning, and could lead to major shortages and price hikes if left unchecked here in the U.S.
NWS isn’t contagious between animals - rather, female flies lay eggs in the wounds or body cavities of animals and then those larvae can go on to cause serious infections (sorry, gross, we know!). The main method for preventing NWS is releasing sterilized flies into the wild to prevent them from successfully reproducing, which the U.S. has already started to do. There are plans to open a $750 million facility next year to produce hundreds of millions of sterilized flies each week (though some worry it will be too late). There’s also a quarantine zone around the farms where cattle have been infected, and a drug that can help prevent and treat infected animals, but the next month or two will be crucial in determining just how bad this gets. Federal funding cuts to the agencies that typically monitor and respond to this haven't helped, but resources are being mobilized now.
Human cases are rare, but possible - there was one travel-related case last year in Maryland that made a full recovery, but cases can be fatal if left untreated. People who work with livestock are at highest risk. The CDC activated a formal emergency response plan to NWS last Thursday, including prep for human infections, though they're uncommon.
In short, New World screwworm isn’t a serious food safety or human health risk, but it may end up being very damaging for livestock industries and drive already sky-high beef prices even higher.
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Sources: Zero Hour Health, NBC, USDA, CNN, APHIS, Hill